1. Field of the Invention
The invention relates generally to semiconducting devices and, more specifically, to PIN photodetector diodes.
2. Description of Related Art
Existing PIN diodes include an absorption region in which incident illumination generates electron-hole charge carriers, and a depletion region in which the density of charge carriers is insufficient to neutralize the fixed charge density of donors and acceptors. Light incident upon the depletion region causes a change in PIN photodiode conductivity. In the context of optical communications, this conductivity change has been advantageously exploited to detect multichannel signals carried on fiber optic cables. Unfortunately, however, presently-existing PIN photodiodes exhibit insufficient linearity when conductivity is measured as a function of illumination. This shortcoming is apparent when the photodiode is employed in the context of cable television to process a plurality of frequency-division-multiplexed, amplitude-modulated vestigial-sideband (AM-VSB) video signals. Nonlinearities in photodiode conductivity as a function of illumination distort the envelope of VSB video signals, providing a degraded video signal at the customer premises.